RENEWABLE ENERGY FOR A GREEN EARTH!

By Paboda Jayawardane | University of Moratuwa | second-year undergraduate.

ABSTRACT

          Renewable energy usage is a trend today. The issues occurring because of conventional energy resources like fossil fuels, coal and gasses are omitted by using renewable energy. It is environmental friendly, with no or low poisonous emissions. It is favorable in health concerns and creates new job opportunities. Out of all Renewable energy types, biomass is the largest job creator and wind power is most sustainable and environmental friendly with the least poisonous emotions followed by hydropower and photovoltaic. So with the correct usage of Renewable energy will lead to sustainable development. Along with those advantages there are some little drawbacks also. But those drawbacks can be omitted by the use of technology and special designs.                                         

ABBREVIATIONS

AC                 Alternative current

ADB              Asian Development Bank

CEB               Central Electricity Board

DC                 Direct current

LV                  Low Voltage

NCRE            Nonconventional renewable energy

PV                  Photovoltaic 

RE                  Renewable energy

SLSEA           Srilanka Sustainable Energy Authority

INTRODUCTION

What are Renewable energies?

Renewable Energies are the Energies which can be replaced or refilled within the human life scale[1] unlike fossil fuels which takes millions of years. Different renewable energy resources like;

• Solar
• Wind
• Hydro power
• Tidal
• Biomass
• Geothermal

became popular within last few years.[1]

In near future RE will be the primary source on power generation. And most of the RE sources are environmental friendly, having no or less emission of poisonous gases, including . (Zero-carbon concept). Countries like Germany, China, UK, Spain, and Sweden are in a trend of moving for the goal 100% RE. And Iceland is a country running with 100% RE.[2]

RENEWABLE ENERGY SOURCES

• Solar Power

Introduction

Radiant light and heat of the sun is used as the source, with use of different technologies those energies are converted into thermal or electrical energy[3]. This is considered as economical and environmental friendly RE due to the low maintenance cost and due to low emission of pollutants. And solar power is versatile. But solar panel systems are weather dependent and storing cost is high. But in topical countries like Srilanka, India, which reserves sun light throughout the daytime solar panel installation is much profitable.

Technology

Mainly 3 technologies are used.

3. Photovoltaic systems.

2. Solar thermal power plants.

3. Solar thermal systems

The rate of increase of global solar market is 5.12%, according to statistics by the end of 2019, amount of 629 GW of solar power was installed throughout the world. China is the leading country for the solar power generation occupying one-third of global installed solar capacity[7]. In 2040 out of the global energy consumption 32% will be created out of solar energy even though in 2019 it was 2%, which shows a clear increase[8].

• Wind power

Introduction

Wind is the moving air due to a pressure difference from high pressure regions to low pressure regions occurring due to suns’ heat. Wind energy is an intermitted energy source (varying power output is obtained, depending on the wind condition). Using the applied technology, the kinetic energy in the wind is converted to electrical energy. There are few drawbacks like habitat loss and threat to bird lives, but by selecting a suitable location most of them can be minimized[1]. Wind farms can be considered as one of the cheapest power generation methods, furthermore offshore farms are more efficient than onshore farms as the offshore wind is more stable and strong compared to onshore but construction cost and maintenance cost are significantly higher[9].

 Technology

Generating system[10]

Component	Work done
Wind turbine	Converts, wind energy to rotational mechanical energy
Gear system and coupling	Steps up speed and transmit to generator
Generator (Generator type used depends on the capacity of the rating system.)	Obtained rotational mechanical energy is converted to electrical energy.
Controller	Initiate appropriate signals by sensing wind direction, output of the wind speed generator and temperature.
Yaw motor gear	Move the blade angle along the vertical axis in a way to receive maximum wind energy

Principle used to calculate power generated out of a turbine is as follows:

v- Velocity of moving air ( )

 – Density of air ( )

A-Area of the rotator ( )

Kinetic energy of moving air in‘t’ time E = =

Power generated by a turbine = =

This shows that the power generated by the turbine is proportional to the third power of wind speed. So when wind speed increases, the power generation will be more efficient[9].

According to statistics by 2019 out of the worlds’ total power consumption wind provides 5.3% it is a 10 % increase over 2018, researches has shown that wind generation capacity is getting doubled within every three years of time. China, US, Germany are the top 3 countries having highest cumulative wind capacity[9].

• Biomass Energy

Introduction

Biomass power is produced by the renewable organic wastes out of various remains of forest, agriculture and livestock[11]. Other than those wastes sewage sludge, landfill gas, manufacturing wastes, enzymes and bacteria are also used. Today, there is a research taking place on algae based biomass. But in biomass, greenhouse gasses are emitted. Even though this type is considered as a carbon neutral energy source as emitted  is equal to the consumption in photosynthesis[1]. A large land is used in constructing the power plant. The biochemical energy stored within is converted to thermal

or electrical energy by applied technology.

Mainly there are 3 types of power plants,

1. Biomass power plants.
2. Biogas power plants.
3. Biofuel (biodiesel and bioethanol) power plants.

Technology

There is a wide range of technologies to utilize biomass.

1. Direct combustion: Here biomass is burned in a stove. An action coming from the past which supplies heat and even can use in the electricity generation also.
2. Fermentation: The production process of bioethanol. Yeast is added to biomass and let to ferment. Then using specific combustion engine bioethanol is burned or “gasohol” is produced by mixing with petrol.
3. Pyrolysis: Within this process solid biomass is converted to the most useful form bio-oil. Then bio-oil is burned and heat and electricity is obtained.
4. Gasification: Here solid biomass is converted to a hot steam which is a gaseous biofuel. Then can burn for heat or electricity production.

• Hydro power

Introduction

This is one of the common RE types that is used in electricity production. Here the kinetic or potential energy stored in water is converted to electrical or mechanical energy using applied technologies. The small scale and large scale plants are found throughout the world. China, Brazil and Canada are the top three countries having the largest hydro power consumption.

Technology

 There are four main power generating methods[15].

1. Conventional (Dams). 
   • Most common type used.
   • Potential energy in stored water is used in electricity production.
   • Power extracted depends on the head (high   difference between outflow and source) and the volume.
2.  Pumped storage.
   • Water is moving between two reservoirs at different elevations.
   • Used to supply peak demands, at low demands excess generation capacity is use to pump water to higher recover and at peaks, the stored water is allowed to flow to the lower reservoir through a turbine.
3. Run of the river
   • Used when the storing capacity is small or null.
   • Water coming from the upstream is used in power generation.
4. Tide
   • The difference in high tides and low tides are used in power generation.
   • Less common type used.

Types and Capacities

Scale	Capacity
Large	Over 2000 MW
Small	Less than 10 MW
Micro	Less than 10 KW
Pico	Less than 5 KW

Formulae for the calculation of power generated:

P- Power (watts)

η- Coefficient of efficiency (Unit less, 0<η<1)

ρ- Density of water (kg/m3)

– Flow rate ( )

 –Mass flow rate (kg/s)

∆h- Head (m)

g- Gravitational acceleration (9.8 )

P = -η ( g =-η ((ρ ) gΔh)

In 2016,24% of electricity were produced by RE, from that 16% were produced by hydropower, in 2019 out of the global electricity consumption 16% was completely supplied by hydropower, which shows a significant increase within 3 years. About 150 countries all over the world use hydropower, in the Asia-Pacific region 32% of total energy consumption was given by hydropower. Flexibility of the resource ,low cost ,low CO2 emission are some advantages of hydropower while ecosystem damage ,loss of lands, methane emissions and failure risks are some disadvantages

Positive effects of RE

• Within a year 35 billion tons of is added to the atmosphere by burning fossil fuels. This result global warming, ocean acidification, green house effects and climatic changes.[16] Other than those geo-climatic changes health concerns and diseases like pneumonia, chronic respiratory diseases, and lung cancers are arising due to huge air pollution. But RE emits zero or a less amount of and greenhouse gasses, and the impacts on the environment is also very low.

• In 2019 population growth rate was reported as 1.1%, with respect to that global energy demand had also increased. By 2035 according to the estimates the energy demand will increase with 90% in developed countries while 20% of the world will still face lack of electricity[17]. But according to the American Petroleum Authority fossils fuels will deplete within 2062 and 2094[18].So to establish the global energy security we have to switch for RE.

• With the installation of RE plants new job opportunities are created in both construction and maintenance phases (Biomass plants make the highest opportunities).With regional development is established. In Germany Green Job concept was created aiming RE jobs[19], research says that 55% of jobs increased since 2004 along with RE usage. So it’ll increase the standards of living of people.

• In economical vise usage of RE is more profitable as it is locally utilized. (Local labor power, locally available materials, local bank systems and other services are used).

• Countries like Srilanka imports fossil fuels for power generation, and always fossil fuel prices show fluctuations. According to the annual central bank report 2020, in 2019 Ceylon Petroleum Cooperation had to averagely pay 68.80$ per barrel, in 2020 45.47$ and in early 2021 it was reported 60- 70 $ per barrel. These price fluctuations create economical imbalance. So RE usage can cut out those costs as they are locally available and can create economic stability[20].

• 13% of world total population do not have access to electricity,40% of the world do not have clean fuels for cooking.(In Baluchistan 90% of rural people do not have electricity).So by installing small or medium scale RE power plants in villages, energy security of rural people can be established[20].

Other general uses are as follows.

Negative effects of RE

• Weather dependent
  • Affected by seasonal variations and climatic conditions.
  • Unavailability of continues and the stable supply of source (wind).
• High cost in installations
• Still generates pollution.
• Biomass emits CO2 and greenhouse gasses.
• Eco systems and the landscape affected.
• Installation occupies a large area to get a considerable output.
• Low efficiency levels.

RENEWABLE ENERGY AND SRILANKA

Being a tropical island, Srianka receives sunlight in 12h per day, rain by 2 monsoons (northeastern and southwestern) and convectional rains with strong wind flows and consisting of good plant coverage. So we are a nation rich with RE.

                       In 2007 SLSEA was established as the primary body in charge of sustainable energy developments. Vision of SLSEA is to enhance energy security by implementing RE while reducing the dependence from imported fuels. They have taken many steps in energy supplying with available resources and the emerging demand matching with sustainable development goals.

Ongoing projects

• Rooftop solar power generation project(under SLSEA)
  • Solar panels are installed in the rooftop of commercial and residential buildings.
  • Started in 2018 and funded by ADB. Already 175 subprojects are installed[21].

• Soorya Bala Sangramaya (under SLSEA and CEB)
  • Solar panels are installed in rooftops of residential, religious and commercial buildings.
  • In 2020, 200 MW and in 2025, 1000MW were expected to be added to the national grid[22].

• Seethawaka Ganga project
• Moragolla hydropower
• Broadlands hydropower
• Uma Oya hydropower
• Energy parks
• Mannar wind park -100MW
• Siyambalanduwa solar park -100MW
• Poonaryan wind and solar park

Apart from above several research are carried to asses solar, wind, hydropower and tidal resources.

According to the annual central bank report 2020,36.8% of electricity generation was out of RE out of that 24.9% was out of hydropower, in 2019 it was 34.9% and 23.8% was out of hydropower. In electricity sector performance NCRE shows a growth rate of 5.9 while in 2019 it was -3.8. It shows a clear growth. According to the expectations in 2050 SLSEA aims for 100% RE usage[23].

NEW TECHNOLOGICAL INFLUENCE.

• Wind and solar

                           Within these few years there are huge improvements in technologies. In England Dr.neil Beattie is on research about a paint or spray that can be applied in cars and rooftops in the generation of solar energy and automatic charging systems are also promoted. In Japan Wind Lenses are used to magnify the wind speed. By this according to research the power output is 2-3 times increased. And today wind blades of different sizes are used to neutralize the power fluctuations[24].

• Distributed generation.

                  

• Power-to-X

      In this technology, the stored electrical energy is converted into heat, hydrogen or a renewable synthetic fuel. This technology is important in aviation, shipping, heavy duty and even in electric cars[26].

• Improvements in energy storage

      Storing capacity of the batteries are being increased. And energy transporting devices are tested within these few years at a research in Harvard University[26].

• Algae Fuel

      In Japan, an algae fuel research has been done this was given in the name “green crude oil”. This fuel doesn’t have any environmental pollution as mentioned[27].

Conclusion

RE is environmental friendly, less air pollution, creates new job opportunities and improve life stands.but there are some negative effects too. Even though RE have some negative effects the net effect is positive. Most of the countries in the world are aiming 100% RE usage in 2040 including Srilanka. And furthermore new technological developments and efficient methods should be introduced increase efficiencies in RE power generation.

REFERENCES

‌[1]- Strossmayer, J. (2014). Positive and Negative  Impacts of Renewable Energy Sources 47 Stanislav Vezmar Anton Spajić Danijel Topić Damir Šljivac Lajos Jozsa. 5(2). https://hrcak.srce.hr/file/201753

[2] – 5 places running on 100% renewable energy. (2020, November 5). World Smart Cities Forum. https://worldsmartcities.org/5-places-running-on-100-renewable-energy/#:~:text=Iceland%20is%20a%20country%20running

‌[3]- Solar energy. (2020, September 24). Wikipedia. https://en.wikipedia.org/wiki/Solar_energy#:~:text=Solar%20energy%20is%20radiant%20light

[4]-Solar Photovoltaic Technology Basics. (n.d.). Energy.gov. Retrieved June 15, 2021, from https://www.energy.gov/eere/solar/solar-photovoltaic-technology-basics#:~:text=Photovoltaic%20(PV)%20materials%20and%20devices%20convert%20sunlight%20into%20electrical%20energy.&text=PV%20materials%20and%20devices%20convert

[5]-Solar thermal power plants – U.S. Energy Information Administration (EIA). (n.d.). Www.eia.gov. https://www.eia.gov/energyexplained/solar/solar-thermal-power-plants.php#:~:text=Solar%20thermal%20power%2Felectric%20generation

[6]-  How a Solar Thermal System Works – Solar Thermal Panels, Herefordshire. (n.d.). Caplor Energy. Retrieved June 15, 2021, from https://caplor.co.uk/technologies/solar-thermal/how-solar-thermal-works/#:~:text=A%20Solar%20Thermal%20system%20works%20by%20harnessing%20the%20sun

[7]- Wikipedia Contributors. (2019, April 25). Solar power by country. Wikipedia; Wikimedia Foundation. https://en.wikipedia.org/wiki/Solar_power_by_country

[8]- Renewables Are Expected to Dominate Global Power Generation by 2040. (n.d.). Www.greentechmedia.com. https://www.greentechmedia.com/articles/read/renewables-expected-to-dominate-global-energy-generation-by-2040

[9]- Wikipedia Contributors. (2018, December 11). Wind power. Wikipedia; Wikimedia Foundation. https://en.wikipedia.org/wiki/Wind_power

[10]- Yumpu.com. (n.d.). wind-power-generation-technologypdf. Yumpu.com. Retrieved June 15, 2021, from https://www.yumpu.com/en/document/view/49106852/wind-power-generation-technologypdf.

[11]- What is Biomass? Biomass is fuel developed from organic materials | ReEnergy Holdings. (2011, September 9). ReEnergy Holdings | Producing Renewable Energy from Biomass Every Day. https://www.reenergyholdings.com/renewable-energy/what-is-biomass/#:~:text=Biomass%20power%20is%20carbon%20neutral

[12]- BIOMASS. (2021). Strath.ac.uk. http://www.esru.strath.ac.uk/EandE/Web_sites/03-04/biomass/background%20info2.html#:~:text=back%20to%20top-

[13]- IEA Task40: Biomass provides 10 percent of global energy use | Biomassmagazine.com. (2013). Biomassmagazine.com. http://biomassmagazine.com/articles/9444/iea-task40-biomass-provides-10-percent-of-global-energy-use

[14]- WBA GLOBAL BIOENERGY STATISTICS 2018.(2018).Google.com. https://worldbioenergy.org/uploads/181203%20WBA%20GBS%202018_hq.pdf.

[15]- Wikipedia Contributors. (2019, February 14). Hydroelectricity. Wikipedia; Wikimedia Foundation. https://en.wikipedia.org/wiki/Hydroelectricity

[16]- Abdallah, L., & El-Shennawy, T. (2013). Reducing Carbon Dioxide Emissions from Electricity Sector Using Smart Electric Grid Applications. Journal of Engineering, 2013, 1–8. https://doi.org/10.1155/2013/845051

[17]- Papp_N. (2011). OECD Green Growth Studies Energy OECD Green Growth Studies. https://www.oecd.org/greengrowth/greening-energy/49157219.pdf

[18]- Puiu, T. (2018, June 7). How long before the world runs out of fossil fuels? ZME Science. https://www.zmescience.com/science/news-science/how-long-fossil-fuels-last-43432/

[19]-  (n.d). Green jobs? Economic impacts of renewable energy in Germany.(2012). http://www.inforum.umd.edu/papers/conferences/2013/germany_lehr_greenjobs_2013.pdf

[20]- Kumar, M. (n.d.). Environmental Impacts of Renewable Energy Resources. Retrieved June 15, 2021, from https://api.intechopen.com/chapter/pdf-download/70874

[21]- Bank, A. D. (2021, March 23). Solar power from the rooftops in Sri Lanka. Asian Development Bank. https://www.adb.org/results/solar-power-rooftops-sri-lanka#:~:text=A%20comprehensive%20database%20of%20all%20175%20project%20installations%20is%20also%20being%20maintained.

[22]- colorlib. (n.d.). Soorya Bala Sangramaya. Www.energy.gov.lk. Retrieved June 15, 2021, from http://www.energy.gov.lk/index.php/en/soorya-bala-sangramaya

[23]- 3.1 Overview. (n.d.). Retrieved June 15, 2021, from https://www.cbsl.gov.lk/sites/default/files/cbslweb_documents/publications/annual_report/2020/en/7_Chapter_03.pdf

[24]- Japan’s Next Generation of Renewable Energy – Our World. (2017). Unu.edu. https://ourworld.unu.edu/en/japans-next-generation-of-renewable-energy

[25]- New technologies for renewable energy to be developed in NE England. (n.d.). EurekAlert! Retrieved June 15, 2021, from https://www.eurekalert.org/pub_releases/2019-02/nu-ntf013119.php

[26]- 5 technologies changing the future of renewable energy. (n.d.). Wartsila.com. https://www.wartsila.com/insights/article/5-technologies-changing-the-future-of-renewable-energy

[27]- A World Finance report: Technological advances in renewable energy. (2014). Worldfinance.com. http://reports.worldfinance.com/technological-advances-in-renewable-energy/.